We are studying the role of the vestibular system and reticular formation in the regulation of motor activity. The effect that stimulation of the labyrinth, or particular receptors, exerts on limb motoneurons will be examined and compared to actions previously observed in neck motoneurons. In addition, the type of labyrinthine information relayed by reticulospinal neurons will be examined. At the level of the brainstem we will study the distribution of activity originating in the utricle within different regions of the vestibular nuclei. All the work will be carried out in cats, principally by means of intracellular and extracellular recording from single cells.